For certain commercially important fish such as sturgeon (family Acipenseridae), adult female fish have enormous value for their roe or caviar. The meat from male fish has only limited economic value, and the cost of rearing males to maturity can far exceed the value of their meat.
The various sturgeon species reach sexual maturity at somewhat different ages, and within each species may reach sexual maturity at differing ages based on factors including food availability and nutritional status. Farm-reared fish may be better fed and faster growing than their wild counterparts, and may reach sexual maturity earlier than in the wild. Scientists at Mote Marine Laboratory's Aquaculture Park (MAP), an indoor aquaculture facility, have found that farm-reared male and female Siberian sturgeon reach sexual maturity at around five years of age, at which point roe can be harvested from female fish. Harvesting involves cutting open the fish, at which point visual inspection can distinguish gender. This gender-determination technique is however lethal to the fish and involves rearing them until they reach maturity.
In aquaculture enterprises, it would be extremely useful to determine the gender of very young (for example, age three or younger) male and female sturgeon in a nonlethal manner. Doing so would allow sturgeon farmers to remove young males and thereby avoid the costs associated with several additional years of rearing less valuable male fish, focus resources on the care and raising of highly valuable female fish, and optimize use of available tank space. Nonlethal methods for early fish gender determination include those described in Vecsei et al., “A noninvasive technique for determining sex of live adult North American sturgeons”, Environmental Biology of Fishes 68: 333-338 (2003); Rainer, “Genetic sex determination in sturgeons: practical application in caviar production”, IST World (2003); Henderson-Arzapalo et al., “Determination of sex by molecular genetic methods in Atlantic sturgeon”, USGS Study Plan Number 02085 (2004); Colombo et al., “Use of Ultrasound Imaging to Determine Sex of Shovelnose Sturgeon”, North American Journal of Fisheries Management 24:322-326 (2004), Craig, “Successful stepping stones to sex identification of lake sturgeon by blood plasma hormones”, Preliminary Proceedings of the 2008 Great Lakes Lake Sturgeon Coordination Meeting (2008); Craig et al., “Sex assignment of lake sturgeon (Acipenser fluvescens) based on plasma sex hormone and vitellogenin levels”, Journal of Applied Ichthyology Special Issue: Proceedings of the Inaugural Meeting of the North American Chapter of the World Sturgeon Conservation Society, Ottawa, Canada, August 19-21, 2008, 25, Issue Supplement s2, pp. 60-67 (October, 2009); and Keyvanshokooh et al., “A review of sex determination and searches for sex-specific markers in sturgeon”, Aquaculture Research, 41, Issue 9, pp. e1-e7 (August, 2010). However, existing gender determination methods generally lack sufficient accuracy or ease of use, especially in young fish.